Dynamo-electric machine.



J. L. BUBNHAM. DYNAMO ELEDTRIG MACHINE. APPLICATION FILED APR. 12, 190B. RENEWED JAN. 2B, 1911- 1,000,776. Patgntedflug. 15,1911.

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Witnesses lnventdrz" A; Joseph Lfiurn'ha r m J. L. BURNHAM. DYNAMO ELECTRIC MACHINE. Arruowmnrrnnn 11212.12, 1909. nnnwnn 11. 20, 1011.

1,000,776. I Patented Aug. 15, 1911.

2 SHEETS-SHEET 2.

Fig. 2.

. Inventor m Joseph L.Burnha'm H I fitt'g.

UNITED STATES PATENT OFFICE.

JOSEPH L, BURNHAM, or scnnnncmnr, NEW YORK. assmuon '10 GENERAL ELEGTRIC NY, A CORPORATION or NEW r Specification of Letters Patent.

Patent-ed Aug. 15, 1911.

Application filed April 12, 1909, Serial 110. 489,515. Renewed January as, 1911. sen-a1 No. 604,875.

To 1111 10/111111 1' t may concern: 1

1111 it known that l, JOSEPH L. Bunxnau, 11 1 11121 11 ot the l nited States. residing at 31110110111111 county of Schcnectatli'. State of New York: have invented certain new and usclul l11111rove111ents 111 l) vna.u1o-.lulcc-' t1'i1- Machines. of which the following is a s ieciliration. l 1

My invention relates to variahlewoltage 1l \'1111loo-electric 11111'c11i11es of the (1111111111- tator type, and its object is to provide 11 machiueot novel design, such that-it may 111 sclt-ex1'iti11g 111111 vet deliver its tulhload critical point below which it will not gen- For such machines 1t has, thcretore,

crate.

been tho'practicc to provide separate exciters; 11y 111 1 invention I am able to -oper-,

ate a self-exciting generatorat full lead over a wide-range of voltage. I accomphsh this by providmg 111 1111111111111 to the mam brushes 1111 auxiliary brush interlnediatc the main brushes, with means for maintaining a substantially. constant 1111l111'ed armature 1111111111 between the auxlhary brushand one 11111111 brush, and means for varying the in duccd armature voltage between the-auxiliary brush and the other main brush. A; portion of the field coils may be connected b1 t. \ve1*11tl.e auxiliary brush and the first main brush, so that the currentin these coils is constant, and the poles on which they are placed have a constant magnetization precisely as in the. ordinary shuntwound generator. ,The variation in the in- 1l111're111voltage between the auxiliary brush and the. other mainbrush results in varying the induced voltage between the two main brushes, so that the 1'11achine mavdeliver its load over. :1. wide rangeof voltage without danger ot" losing its magnetism. 1

My invention will best be understood by 'l'QfQhLllCG to the 11ccou'1pany1ng drawings, in: I wl11'ch- Figure 1 shows diagra n natical1y a, bi-.

polar variable-voltage self-exeiting generator arranged to accordance with my 111venwhich is provided with a commutator B, main commutator brushes 7) 7) displaced front each other,-as is usual, approximately 180 electrical degrees, and an, auxiliary brush 71, substantially midway between the main brushes. In order that the operation of the; machine may most conveniently be understood, l have shown the brushes placed in the positions they would occupy with a Grannnwring armature, or" in a drumwound armature with the end-connections dotted lines 11,that is, the brushes are clirectly opposite the conductors with which the commutator segments on which the brushes bear are in dircct'coimection. G represents the load circuit, which is sup seats the field ma nct, which is in effect bipolar, but which haseach pole split in half.

site poles orpole-portions are connected e tween. the auxihary brush b and the rightstat l is placed in series with these coils for, adjusting the current strength in them, Since the magnetization of the poles on which, these coils are placed determines the armature voltage induced between the auxiliary and the right-handmain brush, and

ciscly the same as in the ordinary shuntvoltage induced between these two brushes the coils E and E and the magnetization of the poles on which they are placed are substantiallyeonstant. On the other two poles or pole-portions arev placed coils E and E, the current. in which is varied so that the magnetization in these poles is in ried. voltage induced between the auxiliary brush:

induced between the auxiliary brush and the fight-hand mam brush, gives a resultant;

of the coils arranged as indicated by'rth'e The field coils E 1 on diametrically 011 of since these coils are connected between these two brushes, the conditions, so far as the induced voltage between these brushes and the magnetization are concerned, are pri,

wound gnerator,tha-t is, the armature is substantially constant, and the currentin' This magnetization determines the; H 1.105 a 1111 the left-hand main brush, which, being 1 variable and added to the constant voltage) variable voltage which is the voltageim'k,

tion; and Fig. 2 shows a modified structure- 1 In F 1g. 1, A represents the armature, 1

plied from the main brushes 6 b. D reprehandmain brush 1)., The usual field rheo pressed onthe load circuit. For instance, if the current in coils E and E ismade the same as the current incoils E and E, and the direction of that current is such .5 that the poles carrying coils E and E are of opposite polarity, as, for instance, north and southrespectively, while the poles carrying coils Eiand E are of south and north polarity, res'jueetively, the voltages induced between the auxiliary brush and both main brushes will be the same, but in opposition, so far as the main brushes are concerned, so that the voltage between the main'brushes will. be zero. E and E gradually reduced, the voltage betweem the mainbrushes will graduallyrise, until, when the current in the coils E and Ex becomes zero, the voltage between the main brushes will be the voltage induced betweenthe auxiliary brush-and the right-hand brush. Now, if the connections of the coils Fl -and E are reversed, and the current is gradually increased, the currents induced in the two portions of the armature between the main brushes will be in-the same direction and an increase of current in coils E and IE will further increase the voltage supplied to the load-circuit. Vhen the current in these coils again reaches the value of the current in coils E and E the machine will be in effect an ordinary-bi-polar generator with the auxiliary brush 5 at the neutral-point with respect to the induced armature 'voltagebetween the main brushes 7) 7). As a convenientarrange ment for varying and reversing the current in coils E and 'E, I have shown a resistance G connected between the auxiliary brush 7)- wind the right-hand main brush 7), so that the .0 voltage-impressed on.t-he terminals of this He represents a' ICSIStiIDCG is eonstant. switch-actmiting member operating two contacts h h, which are connected -to the terminals of the coils E and E. Two series of contacts adapted, to be engaged by the two n'mvahle contacts h ii, respectively, are connected to different. points on the resist-- ance G. If the member ll'ismovedsoas to move contacts-h- 71. to the right, these con tacts onengagmg the first stationary, don -tacts of'the series will connect the (unis-l") and E- acrossltheterminals of resistance-ft must the full voltage is iinprcssedon-thesc mus} As the movement. of thecontacts'is continued, .the points of connection of the field cdils toj-t-he resistance are m'oved"closer, together, wl1en "the contacts l1, -have mace, half a revolution from the )osition.shown, t o field coils are ,hbtl

the terminals of the connected to'the cc the field. "coils therefor-1 short.

' Further movement oftheeonta'ct; hsh j .th'e. points of connection of the eoi'ls1'tijrposi tions farther such a. direction that; the current-in the-coils Now, if the current in coils" nterjof the're'sistanqe and apart on the resistance, but in is. now reversed. tacts h 71 reach the last of the stationary contacts, the coils E and E again have impressed upon them the full voltage betweenthe auxiliary brush and the right-hand main brush, but with that voltage in the opposite direction relative to its direction at starting. Since the current which is commutated beneath the auxiliary brush b is always small, the interpolar space at this brush need not be large. In order to obtain the best commutation under the main brushes, the d'rec: tion of rotation should-be clockwise, as ndiated by the arrow, so that the coils being commutated are approaching the polescof. constant magnetization, so that comniutm tion conditions are the same as in the ordinary shunt-wound machine.

As shown iii Fig. 2, it is not necessa that all the field poles should be sub-divide In that figure the coils Eta-11d E are placed in a single large pole, while coils E and. E? are placed on the two portions of a divided pole, as in Fig. 1. The ope-ration of the modification of Fig. 2 is the same as that of Fig. 1. \Vhen the and E are of o poslte polarity the-currents in coils If} and i the pole on which they' are placed has no magnetization. V hen .the current in coils E and E is zero, the total tlux in the large pole is substantially the same as that n the pole' carrying the coil E. Whenthe chineas a generator.

parts heresliovvn,.,bi it aim in the a pended,

within the .scopeo'fmy invention. What I claim as new and desire to secure by Letters Patent of t -he.United States,'is':

1.; A' variable-voltage selisexcitih' com- "mutator' machine, comprising main Erushe's g1isp laee d from each other by 'su'bstantiall ,180 electrical" de reesfuaj auxiliary-bras intermediate the n'iain'. brushes, mehlisi; foji,

j i-matli'i'e arge; 'be :hrush and;one -inain brush,; and meat -tor inain. brush;

' a. -wiamv iusge pelt-exciting com; m'uta-.tor= machine, compr sing. main rushes" I do not desire to limit myself to the Pill: ticular constu ctio'nv and arrangement of.

claimsto' eo'ver all-modifications w 10h are v .11

maintaining [Substantially'cqnstalitiqduoed immr xi i When the movable con- "poles carrying coils E and E are of the arying the induced, drffi'ature voltag Ibe' tween. .the auxiliary brush .and :the other mutatorrnachine, comprising main brushes displaced from each other by substantially 180 electrical degrees, an auxiliary brush intermediate the main brushes, field poles between said auxiliary brush and 'a main brush, field coils on said poles connected between said auxiliary brush and said main brush, field oles between said auxiliary brush and t e other main brush, field coils on the last-mcntioned poles, and circuit connections for the lastmentioned field co'ils including means for varying the current therein.

4. A variab1evo1tage self-exciting commutator machine, comprising main brushes displaced from each other by substantially 180 electrical degrees, an auxiliary brush intermediate the main brushes, field poles be .tween said auxiliary brush and a main brush, field coils on said poles connected be tween said auxiliar brush and said main brush, field poles fietween said auxiliary brush and the other main brush, field coils on the last-mentioned poles, and circuit connections for the last-mentioned field coils including means for varying and reversing the current therein. 7

'5. A variable-voltage self-exciting commutator machine, comprising main. brushes displaced from each other by substantially 180 electrical degrees, an auxiliary brush intermediate the main brushes, field v oles betweenl tl'ie auxiliary brush and a main brush, field coils on said poles connected between said auxiliary brush and said main brush,

a resistance connected between said auxiliary brush and said main brush, field poles between the auxiliary brush and the other main brush, field coils on the last-mentioned poles, and means for connecting the ter minals of the last-1nentioned field coils to points on said resistance and shifting the points of connection to vary the current in said last-mentioned field coils.

In Witness whereof, I have hereunto set my hand this 10th day of A ril, 1909.

JOSEPH L. URNHAM. Witnesses:

BENJAMIN B. HULL,

HELEN ORFQRD. 

